Cantilever beam deflection calculator
A cantilever is fixed at one end and free at the other, like a balcony or a wall shelf. Enter the length, load and section properties.
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How to use it
- Enter cantilever length, load at the free end, elastic modulus and section moment of inertia.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Tip deflection δ = P L³ ÷ (3 E I). Maximum moment at the fixed end M = P L. Vertical reaction = P.
Example
Inputs: Cantilever length = 2 m, Load at the free end = 2 kN, Elastic modulus = 200 GPa, Section moment of inertia = 1,000 cm⁴. Result: Tip deflection: 2.667 mm; Moment at the fixed end: 4 kN·m; Vertical reaction: 2 kN.
Limits and caveats
- Assumes a fully rigid fixed end; any rotation there adds deflection.
- Covers a point load at the tip only and leaves out the beam self-weight.
Questions about this tool
Why does a cantilever deflect so much more?
With the same load, length and section, a cantilever tip deflects 16 times as much as a simply supported beam with a centre load.
Where is the largest moment?
At the fixed end, equal to the load times the cantilever length.
What if the load is uniform?
For a uniform load w over the full length, deflection is w L⁴ ÷ (8 E I) and the fixed end moment is w L² ÷ 2.